Japanese Patent Application Laid-Open Publication No. 9-195068 (Patent Document 1) discloses a method in which, after Cu strike plating is performed to a lead base material made of Cu alloy as base plating, silver, gold, palladium and others for wire bonding or die bonding are partially plated, and then a semiconductor chip having leads connected thereto is sealed with a sealing body or the like. Also, Japanese Patent Application Laid-Open Publication No. 2003-282798 (Patent Document 2) discloses a semiconductor device using a sealing body in which a thermosetting resin with a high heat conductivity is used as matrix and an inorganic ceramics powder is used as filler (filling material) in order to improve the heat dissipation characteristics.